A study of the secondary and tertiary structure of prokaryotic 5S and tRNA precursor moleculs, that utilizes specific chemical and enzymatic structure probes, will locate an define structural features of RNA processing enzyme recognition sties. This study will focus on 5S rRNA and tRNA precursors isolated from mutant strains of E. coli deficient in RNA processing enzymes, such as RNase E. Purifiation of 5S rRNA precursor molecules will involve re-cloning the E. coli 5S rRNA gene from plasmid PLC19-3 into PBR322. Limited chemical and enzymatic cleavage, over a broad range of solution conditions, of specifically 5'- or 3'-end labeled precursor molecules followed by gel electrophoresis to locate the specific cleavage sites, will yield a comprehensive picture of the structure and dynamical properties used to generate predicton of structure using a recently developed computer-assisted approach that utilizes graphics display and rapid data input modes. Detailed descriptions of the structures of the 5S and tRNA precursor RNAs will reveal aspects of the conformation al properties recognized by the RNA processing enzymes duirng the maturation process.